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Z80 Emulation on 68K Calculators

Posted on 8 September 1998

The following text was written by Michael Bryan Cook:

I just got a TI-89 the other day and was thinking about the fate of my trusty 83 and 85 when I though of this idea. The 92, 92+, and 89 are all 10mhz 68k processors. The rest of the 8x line (except for the 80) are 6mhz Z80s. So it seems to me that the 68k calcs would be fully capable of running some program to emulate the 80x line so that we could run the ASM games for them. This would not only make an easier way to put programs on multiple calcs because there is no need to program in both Z80 and 68k but also this means even on the just released 89 and the fairly new there would be a HUGE library of games. Because they are 4mhz faster they should be able to handle it and the +500k of mem on the 89 and 92+ would easily allow you to hold a program like this no matter how big and still have space for games. This would be a great idea and I'd love it if one of you TI experts could do this. The screens on the 89 and 92(+) are bigger than any other so this would work too. Now I know that this would be hard but look at what we've done! We've put ASM games on the 'impossible' TI-92 and TI-82, hacked the TI-85, made memory expanders, changed the font on the TI-85, and done so many other things that I don't think that it's fair to say we couldn't do it if we set our mind to it!

  Reply to this item

Speed!!
Maddi

Look, to finally finish this speed question...
On my PC, I have a TI-8x Emulator. I have tried
various others, both good and bad, which produce
the same results.

An emulated z80 produces results twice faster than
the real calc, on a 450MHz K6-3.

So, how on earth is an M68k going to cope?? I
don't think they're quite as fast, or even a
third as fast, as a PC processor. Similar
emulation would be required, however.

Reply to this comment    21 April 1999, 17:41 GMT

Re: Speed!! I DID IT
Samir Ribic
(Web Page)

Well, I WRITE Z80 emulator on TI89. Actually
it will emulate ZX Spectrum, popular Europe machine. It is still buggy, but some machine code routines can work. The result is that this 3.5 MHz machine works at about 50% of speed of the original when emulated on 10 MHz TI89. I have great expirience in ZX Spectrum emulators, and
used all possible optimization tricks.

Reply to this comment    14 June 1999, 14:55 GMT


Re: Re: Speed!! I DID IT
duncan smith  Account Info

I was just thinking about this... If one would like to speed up the emulation, one would use a binary tree for lookup of instructions. a linked list would be perfect for this.
Also, the 89/92+ has a workable window system. We could put the display in a window and it would look acceptable, with a modicum of coding. Doing this in TIGCC would be best (duh).

Reply to this comment    31 March 2002, 06:37 GMT


Re: Re: Re: Speed!! I DID IT
Mr.Z  Account Info
(Web Page)

A simple jump table would be more efficient than a binary tree. To get almost full speed (assuming it is not fast enough with other easier tricks), dynamic translation could be used, which would still allow for self-modifying code. The emulated calculator would probably have to have a plain RAM file, because translating to the 68K structures would be dangerous (in terms of causing crashes) & slow. As for the screen image, I hacked a TI-81 ROM to run on a TI-86 emulator, which required mapping the screen in real time, & it turned out quite doable without any windowing support.

Reply to this comment    13 July 2005, 05:16 GMT


????
tim qiao  Account Info

bullshit?

Reply to this comment    14 February 2005, 03:31 GMT

emulator for all
Greg Myers

Someone needs to work on a program to emulate all of the ti calcs to work on any of them, so that once a program is made for one calc it would be able to be emulated for them all, and then many more games would be accessable for everyone. Maybe the emulator would only do the low 80's together, and the higher 80's, like the 89, and the 90's as a different group, because these groups are more similiar to each other, and would be able handle the same stuff at about the same speeds.

Reply to this comment    6 May 1999, 00:06 GMT


Re: emulator for all
burntfuse  Account Info

My thoughts exactly!

Reply to this comment    2 June 2003, 22:23 GMT

Re: Article: "Z80 Emulation on 68K Calculators"
fredyy

donde encuentro el emulador para las ti89\92

Reply to this comment    4 August 1999, 00:46 GMT


Re: Re: Article: Z80 Emulation on 68K Calculators
Mr.Z  Account Info
(Web Page)

Está en Basics -> Calculators -> TI-89, en la sección «EMULATORS».

Reply to this comment    13 July 2005, 05:20 GMT

Re: Article: "Z80 Emulation on 68K Calculators"
Dan E
(Web Page)

Well, emulating one procesor on another is quite a big deal. It would take alot of programming and would even on the 92, probably run slower than on the original calc. It is however, and pretty good idea that should be looked into. Not neccesarily done, but at least looked into.

-Dan

Reply to this comment    9 September 1998, 01:55 GMT

Re: Re: Article: "Z80 Emulation on 68K Calculators"
Chris Wicklein

There are a few reasons why I think such a project
would be a relative waste of time.

The emulation of Z80 functionality would CRAWL.
The emulation of the original host environment
(memory mapped devices would have to be supported) would make the emulation package relatively large (and slower still.) As a result, the emulation wouldn't be suitable for real-time games. Bringing games over to a new calculator isn't a big problem; native games will appear soon enough, they seem to be 95% of what people write, anyway. If someone is itching to begin a project on the TI89, something like a pair of routines for huffman or arithmetic coding and decoding may be more useful.

Reply to this comment    9 September 1998, 04:19 GMT

Re: Re: Re: Article: "Z80 Emulation on 68K Calculators"
The incredible hulk

[The text of this article has been removed by a news editor due to violation of the acceptable use policy.]

Reply to this comment    7 June 1999, 17:45 GMT

Did the other post make you feel dumb?
anonymous

Were you belittled or something?

Reply to this comment    21 June 1999, 09:05 GMT


Re: Re: Re: Re: Article: "Z80 Emulation on 68K Calculators"
Adam Wilson  Account Info

I really don't think that flaming is allowed by the people who run this site. Check the rules, and next time say something constructive.

Reply to this comment    25 April 2001, 11:36 GMT


Re: Re: Re: Article: "Z80 Emulation on 68K Calculators"
duncan smith  Account Info

I is itchin...
Port VTI! it is in c(++), and open source too!

Reply to this comment    31 March 2002, 06:39 GMT

Re: Re: Article: "Z80 Emulation on 68K Calculators"
Alan Johnson
(Web Page)

I think that instead of an onboard emulator, somebody should make a recompiler to dissasemble and recompile the z80 code for 68K. Instead of using your calc's processing power and memory, use your computer's. Onboard calculator emulators/compilors are convenient, but not nearly as memory or speed efficient as computer programs. Forget all of that stuff about processing power and substituting commands; just do it on your PC.

Reply to this comment    10 September 1998, 04:37 GMT

Re: Re: Re: Article: "Z80 Emulation on 68K Calculators"
jared
(Web Page)

THAT IS A GREAT IDEA AND I THINK THAT SHOULD BE DONE INSTEAD OF THE ON CALCULATOR EMULATOR!!!

Reply to this comment    10 September 1998, 05:39 GMT


Re: Re: Re: Article: "Z80 Emulation on 68K Calculators"
Stefan Fausch

I also agreed with this person. It would be much better to decompile the calc programs and recompile then for a different calc on a computer rather than take to time, hassle, and put up with the inevitable speed reduction that comes with using any emulator, not just this one (think about it: 200 mhz PC or a 10 mhz calc ;). It doesn't matter how much faster the processor is; it can only do so many operations per second.

Reply to this comment    12 September 1998, 02:50 GMT


Re: Re: Re: Re: Article: "Z80 Emulation on 68K Calculators"
joey

I also think this is a good idea. But there should be a mac version too. If someone attempts this, try to find a mac programmer to make a simalar app.

Reply to this comment    4 January 1999, 00:25 GMT


Re: Re: Re: Re: Re: Article: "Z80 Emulation on 68K Calculators"
Chris Oden  Account Info

Mac, of course. Mac's need some more stuff, I was thinking of making a TI-89 emulator for Mac, cause I can't seem to find one.

Reply to this comment    29 September 1999, 02:37 GMT


Re: Re: Article: "Z80 Emulation on 68K Calculators"
Justin Karneges

An easy way to avoid a lot of programming would be to compile TI8xEMU with a 68k C compiler making the necessary changes for the 89. I'm not saying it would run fast or anything. =)

Also, the size of the emulator is the least of the memory worries. The TI8x ROMs are. The TI-83 has a 256k ROM. That's like half of the 89's space.

Reply to this comment    10 September 1998, 05:00 GMT


Re: Re: Re: Article: "Z80 Emulation on 68K Calculators"
Patrick Sweeney

No one is saying you need to have the actual ROMs, although it would help.
Being that the 89/92 has the mostly the same functions as the 8x, you could do more of a conversion type of thing, where it uses the 89 version of the function instead.

Reply to this comment    24 February 1999, 19:18 GMT


Re: Re: Re: Re: Article: Z80 Emulation on 68K Calculators
Steven Ford  Account Info

you would need it for rom calls

Reply to this comment    24 May 2006, 21:06 GMT

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